You Xiao-jie

Power distribution control strategy of on-board supercapacitor energy storage system of railway vehicle

Supercapacitor, with high power density and long cycle life, has unique advantages and development prospects in avoiding regeneration failure, improving the braking force in high-speed range and realizing catenary-free operation in urban railway. First, the characteristic curves of the vehicle and characteristics of supercapacitors are studied. Based on matching their characteristics, a power distribution control strategy for on-board supercapacitor energy storage system is proposed. A simulation model and a 3kW experimental platform are set up, in order to simulate single vehicle and single substation. Both of the simulation results and experimental results have verified the feasibility of the control strategy.

An improved voltage balancing compensator for three-level NPC converters

Neutral-point potential oscillation and balancing problem is an inherent drawback hindering the extensively application of Neutral-Point-Clamped three-level converters. Based on the excellent performances of double signal PWM method contributing to the oscillation elimination, this paper proposes an improved neutral-point voltage balancing compensator. The validity and practicability of the proposed algorithm is verified by simulation and experimental results.

Study of heat dissipation for HXD2 locomotive's auxiliary converter

Modern AC traction locomotives, are characteristic of miniaturization, increasing switching frequency and increasing packaging densities, require increased current handling capability of packaged devices in applications related to power conversion. These ever-increasing demands pushed the efficiency of silicon semiconductor power-device to the limit. The heat dissipation in the power system must be taken into account. The temperature field of a product can be picked up to optimize the design and improve the reliability by the technology of thermal analysis in the phase of design. This paper describes results of thermal simulations in the module of HXD2 auxiliary converter with air cooling system. Integrated Thermal Analysis was conducted using the Flotherm and Icepak computational fluid dynamics (CFD) software packages. Influence of air-cooling system parameters on temperature distribution in module was also investigated. The optimized arrangement of the 6 power modules proved the results of thermal simulation of the auxiliary block.

An improved proportional pulse compensation strategy for DC voltage balance of cascaded H-Bridge Rectifier

DC voltage balance strategy is an important control part for Cascaded H-Bridge Rectifier. Proportional pulse compensation strategy is a typical voltage balance strategy, which can realize DC voltage balance with good performance under special working condition. However, the balance effect may be influenced by load current, and it is hard for self adoption under different load conditions. This paper proposes a kind of improved voltage balance strategy through modeling analysis on the circuit on the basis of this proportional pulse compensation strategy. The load current is introduced to the regulator, so as to better realize DC voltage balance under different load conditions. Simulation and experimental results verify the proposed improved strategy.

An equivalent dual three-phase SVPWM realization of the modified 24-sector SVPWM strategy for asymmetrical dual stator induction machine

A modified space vector pulse width modulation (SVPWM) strategy based on vector space decomposition and its equivalent dual three-phase SVPWM realization are proposed in this paper, which is suitable for two-level six-phase voltage inverter fed asymmetrical dual stator induction machines (DSIMs). The DSIM is composed of two sets of symmetrical three-phase stator windings spatially shifted by 30 electrical degrees. The proposed SVPWM technique can reduce the torque ripple and suppress the harmonic currents flowing in stator windings. Above all, the equivalent relationship between the proposed SVPWM technique and the dual three-phase SVPWM technique has been demonstrated, which allows easy implementation for digital signal processor (DSP). Simulation and experimental results, carried out separately on a simulation system and a 3.0 kW DSIM prototype test bench, are presented and discussed.

Pure electric brake of linear induction motor in the linear metro

Pure electric brake of LIM (Linear Induction Motor) for Linear Metro is proposed in this paper. First, a dynamic mathematical model of LIM is derived based on analyzing the end effect. Then a field orientation control scheme is developed through the analysis of the difference between linear motor and rotary motor control. On this basis, giving speed instruction in traction condition and giving force instruction in brake condition to achieve pure electric brake in LIM, which is composed of regenerative brake and reversal brake. This paper also discusses the switching mode from regenerative brake to reversal brake, and removal time of reversal brake. The effectiveness of the proposed control strategy is verified through simulation and experimental results.